Using a Vander Lugt optical correlator, a pre-selected category of objects can be detected in a given scene and through the use of minimum average correlation energy (MACE) filters, a search can be made simultaneously for more than one category of objects in the given scene. Such an ability to perform simultaneous search offers obvious advantages in settings such as a battlefield. If a battle scene had to be searched once for a tank and then for a plane and other enemy vehicles in succession, the searching process can indeed be tedious and time-consuming. MACE filters allow many various categories of objects to be searched for at once in the same scene; however, the output of the correlator that uses the MACE filters only shows that there is or is not at least one of the categories. The output does not distinguish between different categories of objects.